Field of the Disclosure
The disclosure relates to a turbine and more particularly relates to a turbine including a bypass flow passage that bypasses the inside of an impeller chamber, which houses an impeller, and a waste gate valve that opens and closes the bypass flow passage.
Description of Related Art
A supercharging system of an internal combustion engine is provided with a supercharger, in which a compressor impeller disposed in an intake flow passage of the internal combustion engine and a turbine impeller disposed in an exhaust flow passage are connected by a rotating shaft. In the supercharging system, an exhaust gas of the internal combustion engine is applied on the turbine impeller, so as to convert a part of the energy of the exhaust gas into an axial output of the rotating shaft, use the axial output to rotationally drive the compressor impeller, and supercharge intake air of the internal combustion engine. Such a supercharger is also provided with a waste gate mechanism for increasing or decreasing the flow rate of the exhaust gas applied on the turbine impeller. The waste gate mechanism includes a bypass flow passage for the exhaust gas to bypass the turbine impeller, and a waste gate valve for opening and closing the bypass flow passage.
In most cases, the outlet of the bypass flow passage and the waste gate valve for opening and closing the outlet are disposed in the vicinity of the outlet of the turbine impeller. Therefore, the flow passage cross-sectional area of the exhaust gas increases abruptly at the outlet of the turbine impeller, resulting in significant pressure loss at the outlet of the turbine impeller.
In addition, Japanese Patent Publication No. H10-82324 has disclosed a technique of disposing pipe materials separately at the outlet of the turbine impeller and the outlet of the bypass flow passage, and connecting these pipe materials near the distal ends thereof with the respective axes intersecting each other at an acute angle. It is considered that, by disposing separate pipes at the outlet of the turbine impeller and the bypass flow passage in this manner, the flow passage cross-sectional area can be prevented from increasing abruptly at the outlet of the turbine impeller, and therefore increase in pressure loss at the outlet of the turbine impeller can be suppressed.